Charge forming device



Nov. 29, 1938. cv N. MITCHELL 2,138,038

CHARGE FORMING DEVI-GE Original Filed Oct. 21, 192'? KShee'ts-Sheet l Cou riney Nifcbe/Z Nov. 29; 1938. c. N. MITCHELL DEVICE CHARGE FORMI N.

Original Filed 01. 21. 1927 5 Sheets-Sheet 2 i I TTORA Nov. 29, 1938. c; MlTCHELL 2,138,038

CHARGE FORMINGDEVIICE Original Filed Oct. 21, 192.7 3 Sheets-Sheet 3 in 90 gas 6 a5- INVENTOR.

Patented Nov. 29, 1938 CHARGE FORMING DEVICE Courtney N. Mitchell, Berea', Ohio Application 4 Claims.

This invention relates to improving the performance of internal combustion engines, and more particularly to that type using carburetors or other devices for mixing the fuel with the air or oxygen to support combustion. However, it will be evident from the following that a device of this kind would be very useful in forming a preliminary combustible charge in an injection type of engine, such as the commonly known Diesel, and thus securing improved performance. The main object of the invention is to secure maximum performance by improving the combustiblemixture. However, a fan or blower connected to the auxiliary air inlet to raise the. pressure there applied to some amount above the atmospheric pressure has some advantage and such a device can be connected easily, Another object of this invention is to provide means for introducing additional fuel with this air or simultaneously therewith in order to maintain the correct proportions for efficient combustion. A further object is to provide means for introducing water or water vapor into the intake manifold for the purpose of increasing the humidity of the atmosphere therein which adds to the smoothness of engine operation by re-' tarding the rate of combustion, thus preventing or reducing the tendency to knock or detonate and reducing the tendency for the formation of carbon deposits in the combustion space. Another object is to provide. a means of securing approximately atmospheric "pressure in the manifold closely adjacent to the throttle valve, thus securing additional mixture to maintain higher velocities at the desired parts of the manifold. A still further object is to provide a means whereby the distribution of the mixture to all cylinders of a multi-cylinder engine may be maintained equally. To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

The annexed drawings and the following description set forth invdetail certain mechanism embodying the invention, such disclosed means constituting, however, but one of 'various mecha ical farmsin which the principle of the invention may be used.

In said'annexed drawings;

Fig. l is a side elevation of the device as installed in the section of the engine manifold between the carburetor and the distribution header of the manifold; Fig. 2 is a vertical transverse section taken on line 2--2 of Fig. 1, and looking in the direction of the arrows; Fig, 3 is a longictober 21, 1927, Serial mczmsz Renewed May 5, 1934 tudinal section taken on line 3-3 of Fig. 2, and

looking in the direction of the arrows; Fig. 4 is a.portion of the upper tank of arwautomobile radiator showing means for taking off water vapor from the space above the water in this tank; Fig. 5 is a transverse section similar to Fig. 2 and showing an alternative form built up from several parts and using a different, method of fuel and air control; Fig. 6 is a transverse, approximately horizontal section, taken on line 5-6 of Fig. 5, and looking in the direction of the arrows; and Fig. '7 is a fragmentary section similar to Fig. 5, but showing an alternative means of control; Fig. 8 shows a further modification of the device.

Referring 'to the invention as illustrated by Figs. 1, 2, Sand 4, the figure 8 designates the carburetor which is attached to manifold 9 into which manifold the elements are constructed which constitute a part of the present device.

Adjacent the carburetor attachment flange it and in such a position relative to the stream line flow of the carburetor mixture as to discharge into a region of extremely low pressure, is located an air delivery valve II which will be referred to as a booster. This booster consists of a cone seated or needle-valve 12 having spring seat 83 attached to its stem. This spring seat 53 fills most of the sectional area of the booster housing I4, thus acting as a piston or air valve. The valve I2 is held normally out of contact with its seat I5 by means of the spring It, thus permitting air to pass through slotted openings I! along the stem l8 and past the edge of spring-seat l3 and valve [2 into the manifold.

When-the engine is operating with closed or nearly closed throttle, the pumping action of the engine pistons produces .a very material vacuum in the manifold and the atmospheric pressure will thus close booster ll forcing valve member l2 ,into contact with its seat l5 through the pumping efiect acting on disc member l3, and overcoming the relatively light pressure of spring Hi. This action prevents .an excess of air entering the combustible mixture at low speed and light load conditions which would tend to produce erratic action of the engine. the carburetor throttle valve is opened wide, or to a material degree, the pressure rises in the section of the manifold adjacent to the throttle valve to a point only a little below the outside air'pressure. This increase in pressure permits spring It to open valve l2 and the pressure difference permits, an appreciable amount of air to enter through valve seat l5. By locating the when and well around the curve and away from the stream line flow of elements leaving the carburetor, as shown in Fig. 3, a pressure somewhat below the average for that section will be found and a greater amount of air will thus be introduced by booster unit than would be possible if it were located elsewhere. This booster thus permits of the use of more fuel at high speed and full load and will therefore add to the total power output. By the addition of more air by means of carburetor adjustment the explosive mixture may be somewhat reduced in strength at higher speeds and a material increase in the economy of operation thus obtained.

At some distance from the carburetor the sectional area of the manifold isreduced forming a section commonly known as a venturi or diffuser as illustrated at I9. Entering the manifold at, the throat or smallest diameter of this diffuser is another air delivery valve 20 and which is similar to booster valve II but differently operated. Its parts are substantially identical in size and shape to those of booster ll. Valve 2|. corresponds to valve I2, 22 corresponds to spring seat I3, 23 corresponds to housing I4, 24 corresponds to seat l5, and spring 25 is similar to IE, but has a different load rating. Air slots 25 correspond to slots I1 and valve stem 21 is identical with stem l8, save that it is of greater length. The valve 2| is normally held in closed position by means of lever 28 which is actuated through a linkage 29 from the carburetor throttle lever 30. Lever housing 3| is threaded to valye housing cover 32' and through it and the tube elbow fitting 33 and tube 34, humidified air is introduced to the manifold when valve 2| is off its seat.

The upper end of tube 34 is attached by sleeve I nut 35 to hollow bolt 35 into one end of which is soldered inlet tube 31. Bolt 35 is held in place in the wall of radiator hose 38 by means of washers 35 and 40 and nut 4|. Air enters the radiator tank 42 through the overflow pipe 45.

In order to supply additional fuel for the air furnished by the booster II and the air delivery valve 20, a metering valve 44 is provided through which fuel is carried from the carburetor float chamber 45 and tube 46 and introduced around valve 2| with the humidified air. This valve is connected by link 41 with. lever 28 whose position in turn is controlled by the carburetor throttle lever as pointed outabo've, the fuel valve opening thus'being controlled by the carburetor throttle and air admission valve connected thereto.

From the foregoing description it will be understood that when the carburetor throttle valve is openedto, secure maximum engine output, not only does booster add to the available air in the manifold as described, but through linkage connections with the throttle valve lever the pressure of lever 28 on the end of valve stem 21 is released and spring. 25 opens valve 2i permitting water vapor to pass into the manifold. Due to the reduction in diameter of the manifold forming the venturi IS, the velocity at the throat of this venturi is increased to several times the velocity in other sections of the manifold and in accordance with Bernoulli's theorem, this increase in velocity is accompanied by a corresponding decrease in pressure to a value very much below atmospheric pressure. By arranging a gradually divergent opening from the throat of the venturi into' the section of the manifold above or beyond the venturi, this very high velocity head of the tached to the manifold member.

booster unit II at a point close to the wall of the manifold having the least radius of curvature gas mixture will be converted back into pressure head.

' This alternate reducing and increasing of th pressure in the manifold aids in the vaporizing of the fuel and increases the capacity of the supporting air to carry along more evenly the unvaporized elements resulting in a better distribution of power from the various cylinders of a multi-cylinder engine. The reduction in pressure and increase in velocity at each successive venturi causes a further vaporizing of liquids in the gas stream and a breaking down into smaller particles the globules carried by the stream.

Figs. 5 and 6 illustrate an alternative arrangement which is desirable when it is necessary to introduce greater quantities of additional air or where more accurate metering of the air and fuel is required.

In Fig. 5 booster valve 48 is identical with that shown at H in Fig. 2 and serves the same purpose. The difl'user or venturi 49 is introduced into the manifold 5|! as a separate piece which is separate from the carburetor elbow 5|. The external part of this diffuser 49 is turned down so as to form an annulus or circumferential distributing chamber 52 through which, by means of holes 53, air from valve box 54 and fuel from valve 55 is introduced. Valve box 54 is provided with a screen cover 56 and a valve 51 which is controlled by lever 58. Fuel valve 55 is controlled by lever 59 which is connected to air valve lever 58 by link 60 which in turn is connected to carburetor throttle lever 5| by means of link 52. When the carburetor throttle valve is opened wide or to a position giving approximately full power, valve 51 is opened to provide the additional air and fuel valve 55 connected thereto is likewise opened to provide the necessary additional fuel. The construction of a separate Venturi member is very advantageous as it makes possible the polishing of the inner surfaces more effectively than is possible with the integral construction and permits the use of a large number of accurate inlets to the Venturi throat.

In order to .secure a further air delivery and obtain the maximum amount of pressure adjacent to the engine intake valve, a second venturi 53 is located in the manifold and cylinder as that the tubular element shown in Fig. '7 is adapted to be mounted in the manifold line in the same relative position as the element in Fig. 5 in which is mounted the venturi 49. That is, this tubular element has its lower end connected to an elbow in which is mounted a valve similar to the valve 48 of Fig. 5. The venturi is arranged substantiallyas shown in Fig. 5 already described and a fitting substantially the same as 5| and contain-,

ing valve 48 is shown in fragmentary form at- The valve 55 has a slotted passage 61 through it, into which the end of the lever 68 projects. Attached to lever 68, or integral with it, is the disc or paddle 55 which extends partlyacross the manifold passage lil'thus tending to'obstruct the free flow of.

valve 56 away from its seat 13 thus permitting air or combustible mixture contained in the annulus 14 around valve 66 to flow through annulus 15 and holes 15 ,into the gas stream passing the throat of venturi 11 which results from the greatly reduced pressure in the throat of the ventur as already explained.

It is evident from the construction shown that the supplementary gases are taken partly from the manifold below the venturi and past the space 18 adjacent to disc 69 and partly from the air feed chamber 19 which operates automatically like the booster ll shown in Fig. 2 and already explained. In order to compensate for the lack of fuel resulting from an excess of air introduced through air feed chamber 19, an automatic fuel valve 80 isso located in relation to valve seat 13, that it is opened simultaneously with the opening of air valve 56 and fuel is introduced at a rate determined by the pressure drop at the valve seat I3 and the adjustment of thumb screw 8| which controls the maximum opening of valve 80.

In compression ignition engines no carburetor is employed, but ordinarily an air inlet manifold is used in which the inlet air attains velocity of considerable amount. By inserting in a branch of such air manifold a venturi similar to that shown and described above, as for instance the venturi shown at 49 in Fig. 5, a substantial increase in velocity andreduction in pressure is attained at the throat of the venturi. This reduction in pressure provides a difference between the pressure at this point in the manifold and the 1 the discharge from the blower into the annular outside atmosphere, causing air or other gases from this surrounding atmosphere to enter through a suitable fitting such as 54, which will then pass through the orifices 53 and will thus be added to the stream of gases entering this venturi from below.

It is well known that below the critical pressure differences, an increase in the pressure of the high pressure side of an orifice produces a proportional increase in the flow through that orifice. To provide this increase in pressure, the discharge pipe of a compressor or blower is connected to fitting 5| so as to deliver-into this fitting and thence into annular space 52, air or other gas 'under the desired pressure and thereby increase the delivery of fluid to this space. It will be evident that valve 5'| is readily adapted to control space 52 and thence the dischar e through the orifices 53 into the venturi.

The reduced pressure at the throat of the venturi provides means for makingfurther improvements in the charge entering the cylinder. By introducing into such space at 52 of Fig. 5, any liquid capable of being vaporized or atomized, a

further improvement is accomplished in the-contents of the stream entering the engine cylinder.-

fiows through passages 53 into the air stream at or very near to the throat of the venturi. De-

liquid is introduced alone or together with air entering through fitting 54.

It will be evident that as any liquid passes orifices 53 and enters the throat of the venturi, the pressure on it suddenly and very materially drops. This drop in pressure together with the heat usually present in-the manifold causes all or a substantial portion of this liquid to vaporize and thus to enter the main stream above the venturi and then the engine cylinder in condition to participate efficiently in its function in the process of combustion. Such liquid as is not vaporized will become very finely atomized and will thus be readily carried by the air stream. As greater changes in pressure and temperature are required to condense the vapor formed than were required to vaporize it, especially when the air stream is below the saturationpoint, there will be but a limited amount-of condensation after the venturi has been passed.

Fig. 8 illustrating an application of the charge forming device for use on a compression ignition engine of the Diesel type as referred to above, shows a construction similar to that of Fig. 5. In this embodiment the inlet valve 83 controls the flow of air from the intake piping to combustion chamber 84. This piping comprises the fitting 85 which is made in the form of an elbow as shown .or in numerous other shapes to adapt it to the space available. Within this fitting is the venturi 85 having annular channel 81 to which auxiliary air from air fitting 88 is delivered under desired pressure. Several passages 89 deliver this auxiliary air to the main stream which passes thru fitting 85.

A centrifugal blower of similar device indicated at 90 preferably having two outlets, delivers air under considerable pressure to manifold 9|, having passages 9| and 9|" from which the air is delivered thru valve housings 92 and 93 to fittings 8B and 85. Valves 94 and 95, which are preferably interconnected, control the delivery and distribution of air to the above fittings- Bythis means air under one condition of pressure is delivered to fitting 85 and air under another pressure is delivered tothe annular channel 81.

In order to modify the combustion in chamber 84 an auxiliary fluid such as water vapor or other fiuid is introduced through fitting 96, the flow of which is regulated by valve 91. The venturi 98 having passages 99 serves to facilitate the delivery of this auxiliary fluid which is maintained at any desired pressure.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by. any of the following claims or the equivalent of such stated means be employed.

I therefore particularly pointout and distinctly claim as my invention:

1. In combination with an internal combustion engine'including an intake valve, an intake manifold, and a carburetor, a connection between said manifold and said carburetor, automatically actuated means for admitting auxiliary air to said connection, manually actuated means for admitting auxiliary air to said connection, and manually actuated means for admitting additional fuel to said connection.

2. In-combination with an internal combustion engine including an intake valve, an'intake manifold, and a carburetor, a connection between said manifold and said carburetor, automatically actuated means for admitting auxiliary air to said connection, a valve housing communicating with said connection, a manually actuated valve in said housing for controlling the flow through said housing of auxiliary air, a screen protecting the inlet end of said housing, and manually actuated means for admitting additional fuel to said con: nection.

3. In combination with an internal combustion engine including an intake valve, an intake manifold, and a carburetor, a connection between said manifold and said carburetor, automatically actuated means for admitting auxiliary air to said connection manually operable means for actuated valve in said duct, a Venturi member mounted in said passage and forming an annular chamber therein, bores in said Venturi member providing communication between said annular chamber and the throat of said member, a valve housing communicating through said connection wall with said annular chamber, a manually actuated butterfly valve in said housing, a screen protecting the inlet end of said housing, a tube leading from said carburetor and communicating through said connection with said annular chamber, a manually actuated rotary valve for controlling the flow through said tube, means connecting said butterfly valve with said rotary valve to eifect dependent operation thereof, a second Venturi member in said manifold adjacent said intake valve and forming an annular chamber in said manifold, bores in said second Venturi member providing communication between said annular chamber and the throat of said member,

a conduit leading from a source of fluid and communicating through said manifold wall with said manifold annular chamber, a reciprocable valve in said conduit, and manually operable means to actuate said last-named valve.

COUR'I'NEY N. MITCHELL. 

